U.S. patent number 5,473,077 [Application Number 08/337,801] was granted by the patent office on 1995-12-05 for pyrrolidinyl di-carboxylic acid derivatives as metabotropic glutamate receptor agonists.
This patent grant is currently assigned to Eli Lilly and Company. Invention is credited to James A. Monn, Darryle D. Schoepp, Matthew J. Valli.
United States Patent |
5,473,077 |
Monn , et al. |
December 5, 1995 |
**Please see images for:
( Certificate of Correction ) ** |
Pyrrolidinyl di-carboxylic acid derivatives as metabotropic
glutamate receptor agonists
Abstract
The present invention provides novel compounds that affect
certain excitatory amino acid receptors, and are useful in the
treatment of neurological disorders and psychiatric disorders.
Inventors: |
Monn; James A. (Indianapolis,
IN), Schoepp; Darryle D. (Indianapolis, IN), Valli;
Matthew J. (Indianapolis, IN) |
Assignee: |
Eli Lilly and Company
(Indianapolis, IN)
|
Family
ID: |
23322078 |
Appl.
No.: |
08/337,801 |
Filed: |
November 14, 1994 |
Current U.S.
Class: |
548/253; 548/254;
548/531 |
Current CPC
Class: |
A61P
39/02 (20180101); A61P 27/02 (20180101); A61P
25/00 (20180101); C07D 207/16 (20130101); A61P
43/00 (20180101); A61P 25/28 (20180101) |
Current International
Class: |
C07D
207/16 (20060101); C07D 207/00 (20060101); C07D
207/04 (); C07D 403/04 (); C07D 403/14 (); A61K
031/40 (); A61K 031/41 () |
Field of
Search: |
;548/253,254,531
;514/381,423 |
Primary Examiner: Springer; David B.
Attorney, Agent or Firm: Gaylo; Paul J. Boone; David E.
Claims
We claim:
1. A compound of the formula ##STR13## where R.sup.1 and R.sup.2
are independently carboxylic acid or 5-tetrazolyl, or a
pharmaceutically acceptable salt or solvate thereof.
2. A compound as claimed in claim 1 wherein R.sup.1 is carboxylic
acid, or a pharmaceutically acceptable salt or solvate thereof.
3. A compound as claimed in claim 2 wherein R.sup.2 is carboxylic
acid, or a pharmaceutically acceptable salt or solvate thereof.
4. A compound as claimed in claim 3 that is (2R,4R)
4-aminopyrrolidine-2,4-dicarboxylic acid, (2S,4S)
4-aminopyrrolidine-2,4-dicarboxylic acid, or (2R,4S)
4-aminopyrrolidine-2,4-dicarboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
5. The compound as claimed in claim 4 that is (2R,4R)
4-aminopyrrolidine-2,4-dicarboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
6. A compound as claimed in claim 1 wherein R.sup.1 is
5-tetrazolyl, or a pharmaceutically acceptable salt or solvate
thereof.
7. A compound as claimed in claim 6 wherein R.sup.2 is
5-tetrazolyl, or a pharmaceutically acceptable salt or solvate
thereof.
8. A compound as claimed in claim 7 that is (2R,4R)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, (2S,4S)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or (2R,4S)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or a
pharmaceutically-acceptable salt or solvate thereof.
9. The compound as claimed in claim 8 that is (2R,4R)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or a pharmaceutically
acceptable salt or solvate thereof.
10. A method for treating a neurological disorder in a mammal which
comprises administering to a mammal in need thereof a
pharmaceutically-effective amount of a compound of the formula
##STR14## where R.sup.1 and R.sup.2 are independently carboxylic
acid or 5-tetrazolyl, or a pharmaceutically acceptable salt or
solvate thereof.
11. A method as claimed in claim 10 wherein said neurological
disorder is mediated through a cAMP-linked metabotropic glutamate
receptors.
12. A method as claimed in claim 11 wherein said neurological
disorder is mediated through a mGluR2 receptor.
13. A method as claimed in claim 10 employing a compound wherein
R.sup.1 is carboxylic acid, or a pharmaceutically acceptable salt
or solvate thereof.
14. A method as claimed in claim 13 employing a compound wherein
R.sup.2 is carboxylic acid, or a pharmaceutically acceptable salt
or solvate thereof.
15. A method as claimed in claim 14 employing a compound that is
(2R,4R) 4-aminopyrrolidine-2,4-dicarboxylic acid, (2S,4S)
4-aminopyrrolidine-2,4-dicarboxylic acid, or (2R,4S)
4-aminopyrrolidine-2,4-dicarboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
16. A method as claimed in claim 15 employing (2R,4R)
4-aminopyrrolidine-2,4-dicarboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
17. A method as claimed in claim 15 employing (2S,4S)
4-aminopyrrolidine-2,4-dicarboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
18. A method as claimed in claim 10 employing a compound wherein
R.sup.1 is 5-tetrazolyl, or a pharmaceutically acceptable salt or
solvate thereof.
19. A method as claimed in claim 18 employing a compound wherein
R.sup.2 is 5-tetrazolyl, or a pharmaceutically acceptable salt or
solvate thereof.
20. A method as claimed in claim 19 employing a compound that is
(2R,4R) 4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, (2S,4S)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or (2R,4S)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or a pharmaceutically
acceptable salt or solvate thereof.
21. A method as claimed in claim 20 employing (2R,4R)
4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or a pharmaceutically
acceptable salt or solvate thereof.
22. A pharmaceutical formulation comprising an effective amount of
a compound of the formula ##STR15## where R.sup.1 and R.sup.2 are
independently carboxylic acid or 5-tetrazolyl, or a
pharmaceutically acceptable salt or solvate thereof, in combination
with one or more pharmaceutically acceptable carriers, diluents, or
excipients therefor.
23. A pharmaceutical formulation as claimed in claim 22 employing a
compound wherein R.sup.1 is carboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
24. A pharmaceutical formulation as claimed in claim 23 employing a
compound wherein R.sup.2 is carboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
25. A pharmaceutical formulation as claimed in claim 24 employing a
compound that is (2R,4R) 4-aminopyrrolidine-2,4-dicarboxylic acid,
(2S,4S) 4-aminopyrrolidine-2,4-dicarboxylic acid, or (2R,4S)
4-aminopyrrolidine-2,4-dicarboxylic acid, or a pharmaceutically
acceptable salt or solvate thereof.
26. A pharmaceutical formulation as claimed in claim 25 employing
(2R,4R) 4-aminopyrrolidine-2,4-dicarboxylic acid, or a
pharmaceutically acceptable salt or solvate thereof.
27. A pharmaceutical formulation as claimed in claim 24 employing a
compound wherein R.sup.1 is 5-tetrazolyl, or a pharmaceutically
acceptable salt or solvate thereof.
28. A pharmaceutical formulation as claimed in claim 27 employing a
compound wherein R.sup.2 is 5-tetrazolyl, or a pharmaceutically
acceptable salt or solvate thereof.
29. A pharmaceutical formulation as claimed in claim 28 employing a
compound that is (2R,4R) 4-amino-2,4-di (tetrazol-5-yl)pyrrolidine,
(2S,4S) 4 -amino-2,4 -di (tetrazol-5-yl)pyrrolidine, or (2R,4S)
4-amino-2,4-di (tetrazol-5-yl)pyrrolidine, or a pharmaceutically
acceptable salt or solvate thereof.
30. A pharmaceutical formulation as claimed in claim 29 employing
(2R,4R) 4-amino-2,4-di(tetrazol-5-yl)pyrrolidine, or a
pharmaceutically acceptable salt or solvate thereof.
Description
BACKGROUND OF THE INVENTION
In the mammalian central nervous system (CNS), the transmission of
nerve impulses is controlled by the interaction between a
neurotransmitter, that is released by a sending neuron, and a
surface receptor on a receiving neuron, which causes excitation of
this receiving neuron. L-Glutamate, which is the most abundant
neurotransmitter in the CNS, mediates the major excitatory pathway
in mammals, and is referred to as an excitatory amino acid (EAA).
The receptors that respond to glutamate are called excitatory amino
acid receptors (EAA receptors). See Watkins & Evans, Annual
Reviews in Pharmacology and Toxicology, 21:165 (1981); Monaghan,
Bridges, and Cotman, Annual Reviews in Pharmacology and Toxicology,
29:365 (1989); Watkins, Krogsgaard-Larsen, and Honore, Transactions
in Pharmaceutical Science, 11:25 (1990). The excitatory amino acids
are of great physiological importance, playing a role in a variety
of physiological processes, such as long-term potentiation
(learning and memory), the development of synaptic plasticity,
motor control, respiration, cardiovascular regulation, and sensory
perception.
Excitatory amino acid receptors are classified into two general
types. Receptors that are directly coupled to the opening of cation
channels in the cell membrane of the neurons are termed
"ionotropic." This type of receptor has been subdivided into at
least three subtypes, which are defined by the depolarizing actions
of the selective agonists N-methyl-D-aspartate (NMDA),
.alpha.-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA),
and kainic acid (KA).
The second general type of receptor is the G-protein or second
messenger-linked "metabotropic" excitatory amino acid receptor.
This second type is coupled to multiple second messenger systems
that lead to enhanced phosphoinositide hydrolysis, activation of
phospholipase D, increases or decreases in cAMP formation, and
changes in ion channel function. Schoepp and Conn, Trends in
Pharmacological Science, 14:13 (1993). Both types of receptors
appear not only to mediate normal synaptic transmission along
excitatory pathways, but also participate in the modification of
synaptic connections during development and throughout life.
Schoepp, Bockaert, and Sladeczek, Trends in Pharmacological
Science, 11:508 (1990); McDonald and Johnson, Brain Research
Reviews, 15:41 (1990).
The excessive or inappropriate stimulation of excitatory amino acid
receptors leads to neuronal cell damage or loss by way of a
mechanism known as excitotoxicity. This process has been suggested
to mediate neuronal degeneration in a variety of conditions. The
medical consequences of such neuronal degeneration makes the
abatement of these degenerative neurological processes an important
therapeutic goal.
The metabotropic glutamate receptors are a highly heterogeneous
family of glutamate receptors that are linked to multiple
second-messenger pathways. These receptors function to modulate the
presynaptic release of glutamate, and the postsynaptic sensitivity
of the neuronal cell to glutamate excitation. Agonists and
antagonists of these receptors are believed useful for the
treatment of acute and chronic neurodegenerative conditions, and as
antipsychotic, anticonvulsant, analgesic, anxiolytic,
antidepressant, and anti-emetic agents.
It is believed that the administration of antagonist compounds,
which inhibit the activation of neural receptors, will aid in
treating many of the above conditions. Particularly in cases where
excitotoxicity mediates the condition, use of an antagonist
compound may slow or even halt the process of neuronal cell
death.
Antagonists and agonists of neural receptors are classified as
selective for a particular receptor or receptor subtype, or as
non-selective. Antagonists may also be classified as competitive or
non-competitive. While competitive and non-competitive antagonists
act on the receptors in a different manner to produce similar
results, selectivity is based upon the observations that some
antagonists exhibit high levels of activity at a single receptor
type, and little or no activity at other receptors. In the case of
receptor-specific diseases and conditions, the selective
antagonists are of the most value.
A well-known selective agonist of metabotropic receptors is
(1S,3R)-3-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R) ACPD].
Other neurotransmitters include L-glutamate, the most abundant in
situ neurotransmitter, which stimulates both the ionotropic and
metabotropic classes of receptor.
To date there has been no disclosure of an agonist which is
selective for a particular class or subtype of metabotropic
glutamate receptor. Selective antagonists for ionotropic receptors
have been disclosed, as well as general non-selective antagonists.
In order to increase the therapeutic potential for the central
nervous system, site-specific, selective antagonists and agonists
must be developed for each of the different receptor classes and
subclasses.
SUMMARY OF THE INVENTION
This invention relates to a method of treating or preventing a
condition associated with an inappropriate stimulation of a
glutamate receptor in a mammal which comprises administering to a
mammal in need thereof an effective amount of a compound of Formula
I ##STR1## where R.sup.1 and R.sup.2 are independently carboxylic
acid or 5-tetrazolyl, or a pharmaceutically acceptable salt or
solvate thereof.
This invention also provides the novel compounds of Formula I and
the salts and solvates thereof as well as pharmaceutical
formulations employing a compound of Formula I, or a
pharmaceutically acceptable salt or solvate thereof, in combination
with one or more pharmaceutically acceptable carriers, diluents, or
excipients.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS
The terms and abbreviations used in the instant examples have their
normal meanings unless otherwise designated. For example
".degree.C" refers to degrees Celsius; "N" refers to normal or
normality; "mmol" refers to millimole or millimoles; "g" refers to
gram or grams; "ml" means milliliter or milliliters; "M" refers to
molar or molarity; "MS" refers to mass spectrometry; "IR" refers to
infrared spectroscopy; and "NMR" refers to nuclear magnetic
resonance spectroscopy.
As would be understood by the skilled artisan, throughout the
synthesis of the compounds of Formula I it may be necessary to
employ an amino-protecting group or a carboxy-protecting group in
order to reversibly preserve a reactively susceptible amino or
carboxy functionality while reacting other functional groups on the
compound.
Examples of such amino-protecting groups include formyl, trityl,
phthalimido, trichloroacetyl, chloroacetyl, bromoacetyl,
iodoacetyl, and urethane-type blocking groups such as
benzyloxycarbonyl, 4-phenylbenzyloxycarbonyl,
2-methylbenzyloxycarbonyl, 4-methoxybenzyloxycarbonyl, 4-
fluorobenzyloxycarbonyl, 4-chlorobenzyloxycarbonyl, 3-
chlorobenzyloxycarbonyl, 2- chlorobenzyloxycarbonyl,
2,4-dichlorobenzyloxycarbonyl, 4-bromobenzyloxycarbonyl,
3-bromobenzyloxycarbonyl, 4-nitrobenzyloxycarbonyl,
4-cyanobenzyloxycarbonyl, t-butoxycarbonyl, 2-(4
-xenyl)-isopropoxycarbonyl, 1,1-diphenyleth-1-yloxycarbonyl,
1,1-diphenylprop-1-yloxycarbonyl, 2-phenylprop-2-yloxycarbonyl,
2-(p-toluyl)-prop-2-yloxycarbonyl, cyclopentanyloxy-carbonyl,
1-methylcyclopentanyloxycarbonyl, cyclohexanyloxycarbonyl,
1-methylcyclohexanyloxycarbonyl, 2-methylcyclohexanyloxycarbonyl,
2-(4-toluylsulfonyl)-ethoxycarbonyl,
2-(methylsulfonyl)ethoxycarbonyl,
2-(triphenylphosphino)-ethoxycarbonyl, fluorenylmethoxycarbonyl
("FMOC"), 2-(trimethylsilyl)ethoxycarbonyl, allyloxycarbonyl,
1-(trimethylsilylmethyl)prop-1-enyloxycarbonyl,
5-benzisoxalylmethoxycarbonyl, 4-acetoxybenzyloxycarbonyl,
2,2,2-trichloroethoxycarbonyl, 2-ethynyl-2-propoxycarbonyl,
cyclopropylmethoxycarbonyl, 4-(decyloxy)benzyloxycarbonyl,
isobornyloxycarbonyl, 1-piperidyloxycarbonlyl and the like;
benzoylmethylsulfonyl group, 2-nitrophenylsulfenyl,
diphenylphosphine oxide and like amino-protecting groups. The
species of amino-protecting group employed is not critical so long
as the derivatized amino group is stable to the condition of
subsequent reaction (s) on other positions of the intermediate
molecule and can be selectively removed at the appropriate point
without disrupting the remainder of the molecule including any
other amino-protecting group(s). Preferred amino-protecting groups
are t-butoxycarbonyl (t-Boc), allyloxycarbonyl and
benzyloxycarbonyl (CbZ). Further examples of these groups are found
in E. Haslam, PROTECTIVE GROUPS IN ORGANIC CHEMISTRY, (J. G. W.
McOmie, ed., 1973), at Chapter 2; and T. W. Greene and P. G. M.
Wuts, PROTECTIVE GROUPS IN ORGANICS SYNTHESIS, (1991), at Chapter
7.
Examples of such carboxy-protecting groups include methyl,
p-nitrobenzyl, p-methylbenzyl, p-methoxybenzyl,
3,4-dimethoxybenzyl, 2,4-dimethoxybenzyl, 2,4,6-trimethoxybenzyl,
2,4,6-trimethylbenzyl, pentamethylbenzyl, 3,4-methylenedioxybenzyl,
benzhydryl, 4,4'-dimethoxybenzhydryl,
2,2',4,4'-tetramethoxybenzhydryl, t-butyl, t-amyl, trityl,
4-methoxytrityl, 4,4'-dimethoxytrityl, 4,4',4"-trimethoxytrityl,
2-phenylprop-2-yl, trimethylsilyl, t-butyldimethylsilyl, phenacyl,
2,2,2-trichloroethyl, .beta.-(di(n-butyl)methylsilyl)ethyl,
p-toluenesulfonylethyl, 4-nitrobenzylsulfonylethyl, allyl,
cinnamyl, 1-(trimethylsilylmethyl)prop-1-en-3-yl and like moieties.
Preferred carboxy-protecting groups are allyl, benzyl and t-butyl.
Further examples of these groups are found in E. Haslam, supra, at
Chapter 5; and T. W. Greene and P. G. M. Wuts, supra, at Chapter
5.
This invention provides for compounds which are agonists of the
metabotropic neural receptors in the mammalian central nervous
system. The compounds have the general formula: ##STR2## where
R.sup.1 and R.sup.2 are independently carboxylic acid or
tetrazolyl, or a pharmaceutically acceptable salt or solvate
thereof.
As noted, supra, the compounds of the present invention are
derivatives of pyrrolidine which are named and numbered according
to the RING INDEX, The American Chemical Society, as follows.
##STR3##
While all of the compounds of Formula I are believed to process
antagonist activity at the metabotropic receptors, certain groups
of Formula I compounds are more preferred for such use.
As noted supra, this invention includes the pharmaceutically
acceptable salts of the compounds defined by Formula I. A compound
of this invention can possess a sufficiently acidic, a sufficiently
basic, or both functional groups, and accordingly react with any of
a number of organic and inorganic bases, and inorganic and organic
acids, to form a pharmaceutically acceptable salt.
The term "pharmaceutically acceptable salt" as used herein, refers
to salts of the compounds of the above formula which are
substantially non-toxic to living organisms. Typical
pharmaceutically acceptable salts include those salts prepared by
reaction of the compounds of the present invention with a
pharmaceutically acceptable mineral or organic acid or an organic
or inorganic base. Such salts are known as acid addition and base
addition salts.
Acids commonly employed to form acid addition salts are inorganic
acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid,
sulfuric acid, phosphoric acid, and the like, and organic acids
such as p-toluenesulfonic acid, methanesulfonic acid, oxalic acid,
p-bromophenylsulfonic acid, carbonic acid, succinic acid, citric
acid, benzoic, acid, acetic acid, and the like. Examples of such
pharmaceutically acceptable salts are the sulfate, pyrosulfate,
bisulfate, sulfite, bisulfite, phosphate, monohydrogenphosphate,
dihydrogenphosphate, metaphosphate, pyrophosphate, bromide, iodide,
acetate, propionate, decanoate, caprylate, acrylate, formate,
hydrochloride, dihydrochloride, isobutyrate, caproate, heptanoate,
propiolate, oxalate malonate, succinate, suberate, sebacate,
fumarate, maleate, butyne-1,4-dioate, hexyne-1,6-dioate, benzoate,
chlorobenzoate, methylbenzoate, hydroxybenzoate, methoxybenzoate,
phthalate, xylenesulfonate, phenylacetate, phenylpropionate,
phenylbutyrate, citrate, lactate, .gamma.-hydroxybutyrate,
glycolate, tartrate, methanesulfonate, propanesulfonate,
naphthalene-1-sulfonate, napththalene-2-sulfonate, mandelate and
the like. Preferred pharmaceutically acceptable acid addition salts
are those formed with mineral acids such as hydrochloric acid and
hydrobromic acid, and those formed with organic acids such as
maleic acid and methanesulfonic acid.
Salts of amine groups may also comprise quarternary ammonium salts
in which the amino nitrogen carries a suitable organic group such
as an alkyl, alkenyl, alkynyl, or aralkyl moiety.
Base addition salts include those derived from inorganic bases,
such as ammonium or alkali or alkaline earth metal hydroxides,
carbonates, bicarbonates, and the like. Such bases useful in
preparing the salts of this invention thus include sodium
hydroxide, potassium hydroxide, ammonium hydroxide, potassium
carbonate, sodium carbonate, sodium bicarbonate, potassium
bicarbonate, calcium hydroxide, calcium carbonate, and the like.
The potassium and sodium salt forms are particularly preferred.
It should be recognized that the particular counterion forming a
part of any salt of this invention is usually not of a critical
nature, so long as the salt as a whole is pharmacologically
acceptable and as long as the counterion does not contribute
undesired qualities to the salt as a whole.
This invention further encompasses the pharmaceutically acceptable
solvates of the compounds of Formulas I. Many of the Formula I
compounds can combine with solvents such as water, methanol,
ethanol and acetonitrile to form pharmaceutically acceptable
solvates such as the corresponding hydrate, methanolate, ethanolate
and acetonitrilate.
The compounds of the present invention have multiple asymmetric
centers. As a consequence of these chiral centers, the compounds of
the present invention occur as racemates, mixtures of enantiomers
and as individual enantiomers, as well as diastereomers and
mixtures of diastereomers. All asymmetric forms, individual isomers
and combinations thereof, are within the scope of the present
invention.
The terms "R" and "S" are used herein as commonly used in organic
chemistry to denote specific configuration of a chiral center. The
term "R" (rectus) refers to that configuration of a chiral center
with a clockwise relationship of group priorities (highest to
second lowest) when viewed along the bond toward the lowest
priority group. The term "S" (sinister) refers to that
configuration of a chiral center with a counterclockwise
relationship of group priorities (highest to second lowest) when
viewed along the bond toward the lowest priority group. The
priority of groups is based upon their atomic number (in order of
decreasing atomic number). A partial list of priorities and a
discussion of stereochemistry is contained in NOMENCLATURE OF
ORGANIC COMPOUNDS: PRINCIPLES AND PRACTICE, (J. H. Fletcher, et
al., eds., 1974) at pages 103-120.
In addition to the (R)-(S) system, the older D-L system is also
used in this document to denote absolute configuration, especially
with reference to amino acids or amino acid derivatives. In this
system a Fischer projection formula is oriented so that the number
1 carbon of the main chain is at the top. The prefix "D" is used to
represent the absolute configuration of the isomer in which the
functional (determining) group is on the right side of the carbon
atom at the chiral center and "L", that of the isomer in which it
is on the left.
As would be expected, the stereochemistry of the Formula I
compounds is critical to their potency as agonists. The relative
stereo-chemistry shown in the structures is most preferred with the
carboxylic acids preferably in the trans-position, and most
preferably in the 2R,4R orientation. The 4-amino moiety is
preferably cis with regard to the 2-carboxy group, in the preferred
orientation, 4R.
The relative stereochemistry is preferably established early during
synthesis, which avoids stereoisomer separation problems later in
the process. Subsequent synthetic step then employ stereospecific
procedures so as to maintain the preferred chiralty. The preferred
methods of this invention are the methods employing those preferred
compounds.
Scheme I depicted below illustrates the general process used to
synthesize the intermediate compound which serves as the backbone
for the compounds of this invention: ##STR4## wherein R.sup.1b and
R.sup.2b are carboxy-protecting groups, and R.sup.3b and R.sup.4b
are amino-protecting groups.
According to Scheme I, the preferred starting material is
cis-4-hydroxy-D-proline. Though the series of reactions show, this
material is converted into a carboxy- and amino-protected analog of
4-aminopyrrolidine-2,4-dicarboxylic acid. This analog is the
backbone from which the preferred compounds of Formula I may be
synthesized.
As shown in Scheme I, the first step of the synthesis involves the
addition of the carboxy protecting group and the addition of a
functional group (preferred is an aromatic analog, most preferably
benzyl) to the ring nitrogen. The specific reagents and processes
for adding protective groups is well-known and will be described in
detail in the specific examples infra.
After protection of the 2-carboxy and ring nitrogen, the 4-hydroxy
group is oxidized to an oxo group which defines the cyclic ketone
intermediate shown. This intermediate is then disubstituted at the
C4 position to add the 4-carboxy and 4-amino moieties. This step
generally result in the formation of diastereomers at the C4
position, which are preferably separated to leave only the desired
enantiomer. These 4-substituted groups are protected and the N1
moiety removed to define the final intermediate shown. Subsequent
removal of the blocking groups results in the compounds of Formula
I.
All specific reagents used and conditions employed in the Scheme I
will be identified in the specific examples infra.
Those compounds of Formula I in which R.sup.1 is tetrazolyl are
prepared from the substituted 4-pyrrolidinone depicted in Scheme I,
supra.
The following Preparations and Examples further illustrate the
compounds of the present invention and the methods for their
synthesis. The Examples are not intended to be limiting to the
scope of the invention in any respect, and should not be so
construed. All experiments were run under a positive pressure of
dry nitrogen or argon. All solvents and reagents were purchased
from commercial sources and used as received, unless otherwise
indicated.
Proton nuclear magnetic resonance (.sup.1 H NMR) spectra were
obtained on a GE QE-300 spectrometer at 300.15 MHz, a Bruker AM-500
spectrometer at 500 MHz, or a Bruker AC-200P spectrometer at 200
MHz. Free atom bombardment mass spectroscopy (FABMS) was performed
on a VG ZAB-2SE instrument. Field desorption mass spectroscopy
(FDMS was performed using either a VG 70SE or a Varian MAT 731
instrument.
Optical rotations were measured with a Perkin-Elmer 241
polarimeter. Chromatographic separation on a Waters Prep 500 LC was
generally carried out using a linear gradient of the solvents
indicated in the text unless otherwise specified.
The reactions were generally monitored for completion using thin
layer chromatography (TLC). Thin layer chromatography was performed
using E. Merck Kieselgel 60 F.sub.254 plates, 5 cm.times.10 cm,
0.25 mm thickness. Spots were detected using a combination of UV
and chemical detection (plates dipped in a ceric ammonium molybdate
solution [75 g of ammonium molybdate and 4 g of cerium (IV) sulfate
in 500 ml of 10% aqueous sulfuric acid] and then heated on a hot
plate). Preparative centrifugal thin layer chromatography was
performed on a Harrison Model 7924A Chromatotron using Analtech
silica gel GF rotors.
Cation exchange chromatography was performed with Dowex.RTM.
50X8-100 ion exchange resin. Anion exchange chromatography was
performed with Bio-Rad AG.RTM. 1-X8 anion-exchange resin (acetate
form converted to hydroxide form). Flash chromatography was
performed as described by Still, et al., Journal of Organic
Chemistry, 43:2923 (1978).
Optical rotations are reported at the sodium-D-line (354 nm).
Elemental analyses for carbon, hydrogen, and nitrogen were
determined on a Control Equipment Corporation 440 Elemental
Analyzer, or were performed by the Universidad Complutense
Analytical Centre (Facultad de Farmacia, Madrid, Spain). Melting
points were determined in open glass capillaries on a Thomas Hoover
capillary melting point apparatus or a Buchi melting point
apparatus, and are uncorrected.
Preparation 1
Preparation of
2R,4R-1-Benzyloxycarbonyl-4-hydroxypyrrolidine-2-carboxylic acid
##STR5##
cis-4-Hydroxy-D-proline (10 g, 76.3 mmol) was dissolved in 5%
aqueous sodium bicarbonate (800 ml), then a solution of benzyl
chloroformate (34.1 g, 200 mmol) in toluene (400 ml) was added over
a 30 minute period. The resulting reaction mixture was stirred at
room temperature for 3 days. The reaction mixture was acidified
with concentrated hydrochloric acid, extracted with ethyl acetate,
washed with brine, dried over magnesium sulfate, and concentrated
in vacuo to afford the title compound as a light yellow solid
(20.42 g, 77 mmol) 100%. mp=102.degree.-105.degree. C. FDMS=266
M.sup.+ +1. [.alpha.].sub.D =+125.43.degree..
Analysis for C.sub.13 H.sub.15 NO.sub.5 : Theory: C, 58.86; H,
5.70; N, 5.28. Found: C, 58.59; H, 5.65; N, 5.41.
Preparation 2
Preparation of ethyl
(2R,4R)-1-benzyloxycarbonyl-4-hydroxypyrrolidine-2-carboxylate
##STR6##
p-Toluenesulfonic acid monohydrate (1.45 g, 7.6 mmol was added to a
solution of
(2R,4R)-1-benzyloxycarbonyl-4-hydroxypyrrolidine-2-carboxylic acid
(20.30 g, 76.5 mmol) in ethanol (100%, 1000 ml) and refluxed
overnight with removal of water via a Dean-Stark trap filled with 3
.ANG. sieves. The reaction mixture was concentrated under reduced
pressure, then partitioned between a saturated sodium bicarbonate
solution and ethyl acetate. The layers were separated and the
aqueous phase extracted with ethyl acetate (3.times.500 ml). All
organic phases were combined, washed with brine, dried over
potassium carbonate, and concentrated in vacuo to afford the crude
product which was purified by high performance liquid
chromatography (10% ethyl acetate/hexanes to 50% ethyl
acetate/hexanes) affording the title compound (21.25 g, 72.5 mmol)
95%. FDMS=293 M.sup.+. [.alpha.].sub.D =+43.26.degree..
Analysis for C.sub.15 H.sub.19 NO.sub.5 : Theory: C, 61.42; H,
6.53; N, 4.77. Found: C, 61.29; H, 6.65; N, 4.90.
Preparation 3
Preparation of ethyl
(2R,4R)-1-benzyl-4-hydroxypyrrolidine-2-carboxylate ##STR7##
Ethyl
(2R,4R)-1-benzyloxycarbonyl-4-hydroxypyrrolidine-2-carboxylate
(21.15 g, 72.1 mmol) was added to an ethanolic suspension of 5%
palladium on activated carbon (4.5 g in 275 ml) and exposed to
hydrogen gas (60 psi) at room temperature for 2.5 hours. The
reaction mixture was filtered through CELITE.RTM. and concentrated
in vacuo no yield the crude product (11.27 g, 71 mmol, 98%). The
crude product was reconstituted in methylene chloride (200 ml),
treated with N,N-diisopropylethylamine (18.10 g, 140 mmol), and
then benzyl bromide (14.38 g, 84 mmol) in methylene chloride (100
ml) was added dropwise. Upon complete addition the resulting
reaction mixture was stirred at room temperature overnight. water
(100 ml) was added to the reaction mixture and the product
extracted with diethyl ether (3.times.250 ml). All organic phases
were combined, washed with brine, dried over potassium carbonate,
and concentrated in vacuo to yield the crude product which was
purified by HPLC (10% ethyl acetate/hexanes to 50% ethyl
acetate/hexanes) affording the title compound (12.35 g, 50 mmol)
71%. FDMS=249 M.sup.+. [.alpha.].sub.D =+167.68.degree.
Analysis for C.sub.14 H.sub.19 NO.sub.3.0.4 water: Theory: C,
65.55; H, 7.78; N, 5.46. Found: C, 65.70; H, 7.64; N, 5.46.
Preparation 4
Preparation of Ethyl (2R)-1-benzyl-4-oxopyrrolidine-2-carboxylate
##STR8##
Oxalyl chloride (16.0 g, 126 mmol, 11 ml) was added dropwise to a
solution of anhydrous methylene chloride (300 ml) and
dimethylsulfoxide (13.12 g, 168 mmol) at -78.degree. C. The
reaction mixture was allowed to equilibrate for 10 minutes, after
which time a solution of ethyl
(2R,4R)-1-benzyl-4-hydroxypyrrolidine-2-carboxylate (20.90 g, 84
mmol) in methylene chloride (100 ml) was added dropwise at a rate
to keep the reaction temperature below -60.degree. C. Upon complete
addition the reaction mixture was allowed to stir at -78.degree. C.
for 2 hours, then triethylamine (25.50 g, 252 mmol) was added
dropwise. After complete addition, the reaction was allowed to warm
to room temperature. Water (50 ml) was added to the reaction
mixture, the pH was adjusted to 10 with sodium bicarbonate, and the
product extracted with diethyl ether (3.times.200 ml). All organic
phases were combined, washed with brine, dried over potassium
carbonate, and concentrated in vacuo to yield crude product which
was purified by high performance liquid chromatography (10% ethyl
acetate/hexanes to 50 % ethyl acetate/hexanes) affording the title
compound (20.44 g, 82.7 mmol) 98%. FDMS=247 M.sup.+.
[.alpha.].sub.589 =+31.10.degree..
Analysis for C.sub.14 H.sub.17 NO.sub.3 : Theory: C, 68.00; H,
6.93; N, 5.66. Found: C, 67.76; H, 6.91; N, 5.65.
Preparation 5
Preparation of diethyl
(2R,4R)-1-benzyl-4-aminopyrrolidine-2,4-dicarboxylate ##STR9##
Potassium cyanide (13.36 g, 205 mmol) was added in one portion to a
solution of ethyl (2R)-1-benzyl-4-oxopyrrolidine-2-carboxylate
(20.30 g, 82 mmol) and ammonium carbonate (19.21 g, 246 mmol), in
ethanol (500 ml) and water (500 ml). The resulting reaction mixture
was heated at 55.degree. C. for 2 days. Sodium hydroxide (90.0 g,
2.25 mol) was added and the reaction was warmed under refluxed
overnight. The reaction mixture was chilled to 0.degree. C.,
acidified to pH 1 with concentrated hydrochloric acid (.about.200
ml), and concentrated in vacuo. Ethanol (500 ml) was added to the
crude amino diacid mixture and then concentrated to dryness
(5.times.), so as to remove residual water. The resulting anhydrous
amino diacid was then reconstituted in ethanol (1 L), cooled to
0.degree. C., and treated with thionyl chloride (39.02 g, 328
mmol). Upon complete addition the reaction mixture was refluxed for
three days. The solids were filtered and the filtrate was
concentrated in vacuo. The crude product was partitioned between 3N
sodium hydroxide, sodium chloride, and ethyl acetate. The ethyl
acetate was removed and the aqueous phase extracted with ethyl
acetate (3.times.1 L). All the organic phases were combined, washed
with brine, dried over potassium carbonate and concentrated in
vacuo to yield a dark red oil, which was purified by HPLC (10%
ethyl acetate/hexanes to 90% ethyl acetate/hexanes) affording the
title compound (12.14 g, 38 mmol) 46%. FDMS=320 M.sup.+.
[.alpha.].sub.D =+203.29.degree..
Analysis for C.sub.17 H.sub.24 N.sub.2 O.sub.4 : Theory: C, 63.73;
H, 7.55; N, 8.74. Found: C, 63.74; H, 7.64; N, 8.50.
Preparation 6
Preparation of diethyl
(2R,4R)-1-benzyl-4-(tert-butyloxycarbonylamino)pyrrolidine-2,4-dicarboxyla
te ##STR10##
Di-tert-butyl-dicarbonate (12.26 g, 56.2 mmol) was added in one
portion to a solution of diethyl
(2R,4R)-1-benzyl-4-aminopyrrolidine-2,4-dicarboxylate (12.0 g, 37.5
mmol) in methylene chloride (400 ml) and the resulting reaction
mixture was stirred at room temperature overnight. Sodium hydroxide
(100 ml of a 0.5N solution) was added to the reaction mixture and
the product extracted with diethyl ether. All the organic phases
were combined, washed with brine, dried over potassium carbonate,
and concentrated in vacuo to yield the crude product, which was
purified by high performance liquid chromatography (10% ethyl
acetate/hexanes to 50% ethyl acetate/hexanes) affording the title
compound (15.92 g, 37.5 mmol), 100%. FDMS=420 M.sup.+.
[.alpha.].sub.D =+99.04.degree..
Analysis for C.sub.22 H.sub.32 N.sub.2 O.sub.6 : Theory: C, 62.84;
H, 7.67; N, 6.66. Found: C, 63.06; H, 7.58; N, 6.51.
Preparation 7
Preparation of diethyl
(2R,4R)-4-(tert-butyloxycarbonylamino)pyrrolidine-2,4-dicarboxylate
##STR11##
Diethyl
(2R,4R)-1-benzyl-4-(tert-butyloxycarbonylamino)pyrrolidine-2,4-dicarboxyla
te (15.80 g, 37.5 mmol) was added to an ethanolic suspension (100
mL) of 5% Pd/C (4.0 g) and exposed to hydrogen gas (60 psi) for 4
hours at room temperature. The reaction mixture was filtered
through CELITE.RTM. and concentrated in vacuo to yield the crude
product, which was purified by high performance liquid
chromatography (20% ethyl acetate/hexanes to 80% ethyl
acetate/hexanes) affording the title compound (10.48 g, 31.7 mmol)
85%. mp=58.degree.-60.degree. C.
FDMS=331 M.sup.+ +1. [.alpha.].sub.D =+10.63.degree..
Analysis for C.sub.15 H.sub.26 N.sub.2 O.sub.6 : Theory: C, 54.53;
H, 7.93; N, 8.48. Found: C, 54.29; H, 7.79; N, 8.42.
EXAMPLE 1
Preparation of (2R,4R) 4-aminopyrrolidine-2,4-dicarboxylic acid
##STR12##
A solution of 2R,4R-Diethyl
4-(tert-butyloxycarbonylamino)pyrrolidine-2,4-dicarboxylate (1.00
g, 3.00 mmol) in diethyl ether (35 ml) was chilled to 0.degree. C.,
purged with anhydrous hydrogen chloride gas, and allowed to warm to
room temperature as it stirred for one hour. The reaction mixture
was concentrated to dryness, and stirred in a 1:1 mixture of
tetrahydrofuran/1N sodium hydroxide (20 ml total volume) at room
temperature overnight. The reaction mixture was neutralized,
concentrated to dryness, reconstituted in water and adjusted to pH
2 with 1N hydrochloric acid, and purified by cation exchange
chromatography (5% pyridine/water) affording the title compound
(0.40 g, 2.30 mmol) 77%. mp=>250.degree. C.
FDMS=315 M.sup.+ +1. [.alpha.].sub.D =+93.16.degree..
Analysis for C.sub.6 H.sub.10 N.sub.2 O.sub.4 : Theory: C, 41.38;
H, 5.79; N, 16.08. Found: C, 41.23; H, 5.78; N, 15.87.
The Formula I compounds of the present invention are agonists of
certain metabotropic excitatory amino acid receptors. Specifically,
the Formula I compounds are agonists of the negatively-coupled
cAMP-linked metabotropic glutamate receptors. Therefore, another
aspect of the present invention is a method of affecting an
excitatory amino acid receptor in mammals, which comprises
administering to a mammal requiring modulated excitatory amino acid
neurotransmission a pharmacologically-effective amount of a
compound of Formula I. The term "pharmacologically-effective
amount" is used to represent an amount of the compound of the
invention which is capable of affecting the excitatory amino acid
receptors. By affecting, a compound of the invention is acting as
an agonist. When a compound of the invention acts as an agonist,
the interaction of the compound with the excitatory amino acid
receptor mimics the response of the interaction of this receptor
with its natural ligand (i.e. L-glutamate).
The particular dose of compound administered according to this
invention will, of course, be determined by the particular
circumstances surrounding the case, including the compound
administered, the route of administration, the particular condition
being treated, and similar considerations. The compounds can be
administered by a variety of routes including oral, rectal,
transdermal, subcutaneous, intravenous, intramuscular, or
intranasal routes. Alternatively, the compound may be administered
by continuous infusion. A typical daily dose will contain from
about 0.001 mg/kg to about 100 mg/kg of the active compound of this
invention. Preferably, daily doses will be about 0.05 mg/kg to
about 50 mg/kg, more preferably from about 0.1 mg/kg to about 20
mg/kg.
A variety of physiological functions have been shown to be subject
to influence by excessive or inappropriate stimulation of
excitatory amino acid transmission. The Formula I compounds of the
present invention are believed to have the ability to treat a
variety of neurological disorders in mammals associated with this
condition, including acute neurological disorders such as cerebral
deficits subsequent to cardiac bypass surgery and grafting,
cerebral ischemia (e.g. stroke and cardiac arrest), spinal cord
trauma, head trauma, perinatal hypoxia, and hypoglycemic neuronal
damage. The Formula I compounds are believed to have the ability to
treat a variety of chronic neurological disorders, such as
Alzheimer's disease, Huntington's Chorea, amyotrophic lateral
sclerosis, AIDS-induced dementia, ocular damage and retinopathy,
cognitive disorders, and idopathic and drug-induced Parkinson's.
The present invention also provides methods for treating these
disorders which comprises administering to a patient in need
thereof an effective amount of a compound of Formula I.
The Formula I compounds of the present invention are also believed
to have the ability to treat a variety of other neurological
disorders in mammals that are associated with glutamate
dysfunction, including muscular spasms, convulsions, migraine
headaches, urinary incontinence, psychosis, drug tolerance,
withdrawal, and cessation (i.e. opiates, benzodiazepines, nicotine,
cocaine, or ethanol), smoking cessation, anxiety and related
disorders (e.g. panic attack), emesis, brain edema, chronic pain,
sleep disorders, Tourette's syndrome, attention deficit disorder,
and tardive dyskinesia. Therefore, the present invention also
provides methods for treating these disorders which comprise
administering to a patient in need thereof an effective amount of
the compound of Formula I.
The compounds of the present invention are agonists of cAMP-linked
metabotropic glutamate receptors. These compounds are negatively
coupled through the receptor to adenyl cyclase, inhibiting the
formation of cyclic adenosine monophosphate. The Formula I
compounds of the present invention are, therefore, believed to have
the ability to treat a variety of psychiatric disorders, such as
schizophrenia, anxiety and related disorders (e.g. panic attack),
depression, bipolar disorders, psychosis, and obsessive compulsive
disorders. The present invention also provides methods for treating
these disorders which comprises administering to a patient in need
thereof an effective amount of a compound of Formula I.
The affinity of the compounds for metabotropic glutamate receptors
was demonstrated by the selective displacement of
(1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-sensitive [.sup.3
H]glutamate binding to rat brain cell membranes. The binding of
[.sup.3 H]glutamate ([.sup.3 H]Glu) was conducted with crude
membranes of rat forebrain as described by Schoepp and True.
Schoepp and True, Neuroscience Letters, 145:100-104 (1992); Wright,
et al., Journal of Neurochemistry, 63:938-945 (1994).
In addition to the binding assays described supra, representative
compounds of Formula I were also tested for their ability to affect
the cAMP-linked metabotropic glutamate receptors. These compounds
were tested for their ability to decrease forskolin-stimulated cAMP
formation in the ram hippocampus and the rat cerebral cortex, using
the procedures described in Schoepp and Johnson. Schoepp and
Johnson, Neurochem. Int., 22:277-283 (1993). Those compounds tested
did decrease this cAMP formation.
Functional Assays Employing Cloned Subtypes of Metabotropic
Receptor
The appropriate functional assay using recombinant metabotropic
glutamate receptors, adenylate cyclase activity or
phosphatidylinositol hydrolysis, is performed substantially as
before using standard procedures.
(a) Adenylate Cyclase Activity.
Adenylate cyclase activity is determined in initial experiments in
transfected mammalian cells, using standard techniques. See, e.g.,
N. Adham, et al., supra,; R. L. Weinshank, et al Proceedings of the
National Academy of Sciences (USA), 89:3630-3634 (1992), and the
references cited therein.
Mammalian cells (the cell line AV12-664 is especially preferred)
are stably transfected with a plasmid comprising the cloned
metabotropic glutmate receptor. The cells are maintained in a
medium consisting of Dulbecco's Modified Eagle's Medium (DMEM)
containing 5% dialyzed fetal calf serum, 10 mM HEPES buffer (pH
7.3), 1 mM sodium pyruvate, 1 mM glutamine, and 200 .mu.g/ml
hygromycin.
For the assay the cells are disassociated from stock culture flasks
with trypsin, and planted in 24-well plastic culture dishes (15 mm
wells) at a density of 500,000-700,000 cells per well using the
same culture medium. After twenty four hours incubation in a
humidified carbon dioxide incubator, the cell monolayers are washed
with buffer (Dulbecco's phosphate-buffered saline containing 0.5 mM
isobutylmethylxanthine and 3 mM glucose) and then incubated in the
same buffer at 37.degree. C. for 30 minutes. The monolayers are
then washed six additional times with buffer.
Drugs and forskolin, or forskolin alone, dissolved in buffer, are
added after the final wash. After incubating for 20 minutes at
37.degree. C., 0.5 ml of 8 mM EDTA is added to each well. The
plates are then placed in a boiling water bath fox about four
minutes. The supernatant fluids are then recovered from the wells
and lyophilized. Cyclic adenosinemonophosphate determinations are
carried out on the lyophilized samples using commercially available
radioimmunoassay kits, following the manufacturer's instructions.
The cAMP level in wells containing drug are the compared to the
forskolin controls.
(b) Phosphatidylinositol Assay
Phosphatidylinositol hydrolysis in clonal cell lines of AV12
harboring a plamid expressing the cloned metabotropic glutamate
receptor is measured in response to glutamate agonists as a
functional assay for metabotropic glutamate receptor activity
according to D. Schoepp, Trends in Pharmaceutical Sciences, 11:508
(1990).
Twenty-four-well tissue-culture vessels are seeded with
approximately 250,000 cells per well in Dulbecco's Minimal
Essential Media (D-MEM) (in the absence of glutamic acid) which
contained 2 mM glutamine and 10% dialyzed fetal calf serum. After
24 hours growth at 37.degree. C. the media is removed and replaced
with fresh media containing four microcuries of [.sup.3
H]myoinositol per well and the cultures are incubated a further 16
to 20 hours. The media is then removed and the cells in each well
are washed with serum free medium containing 10 mM lithium
chloride, 10 mM myoinositol, and 10 mM HEPES (2.times.1 ml washes).
After the final wash, 0.5 ml of washing solution is added
containing the appropriate concentrations of drugs and
vehicles.
If the particular assay is also testing antagonists, a ten minute
incubation is performed prior to agonist induction. Cells are
incubated for about one hour at 37.degree. C. in 95%:5% O.sub.2
:CO.sub.2 or as appropriate for time course. The reactions are
terminated by removing media and adding 1 ml of cooled 1:1
acetone:methanol followed by induction on ice for a minimum of
twenty minutes.
These extracts are then removed and placed in 1.5 ml centrifuge
tubes. Each well is washed with 0.5 ml water and this wash is added
to the appropriate extract. After mixing and centrifugation, each
aqueous supernatant is processed by chromatography on a QMA
SEP-PAK.RTM. column, which had previously been wetted and
equilibrated by passing 10 ml of water, followed by 8 ml of 1M
triethylammonium hydrogen carbonate (TEAB), followed by 10 ml of
water through the column.
The assay supernatants contining the water soluble [.sup.3
H]inositol phosphate are passed over the columns. This is followed
by a 10 ml water wash and a 4 ml wash with 0.02M TEAB to remove
[.sup.3 H]inositol precursors. [.sup.3 H]Inositol phosphate is
eluted with 4 ml of 0.1M TEAB into scintillation vials and counted
in the presence of scintillation cocktail. Total protein in each
sample is measured using standard techniques. Assays are measured
as the amount of [.sup.3 H]inositol phosphate release per milligram
of protein.
These types of assay, employing different subtypes of cloned
metabotrapic receptors, may be used to determine which compounds
have selective affinity in that they bind to one subtype of
receptor with a greater affinity than another subtype. In
performing such experiments with some of the compounds of the
present invention, it has been demonstrated that some compounds of
the present invention act as agonists with the cAMP-linked
metabotropic glutamate receptors, while showing less activity with
the phosphatidylinositol-linked metabotropic glutamate
receptors.
The compounds of Formula I are usually administered in the form of
pharmaceutical compositions. These compounds can be administered by
a variety of routes including oral, rectal, transdermal,
subcutaneous, intravenous, intramuscular, and intranasal. These
compounds are effective as both injectable and oral compositions.
Such compositions are prepared in a manner well known in the
pharmaceutical art and comprise at least one active compound.
The present invention also includes pharmaceutical compositions
which contain, as an active ingredient, a compound of Formula I
associated with pharmaceutically acceptable carriers. In making the
compositions of the present invention the active ingredient is
usually mixed with an excipient, diluted by an excipient or
enclosed within such a carrier which can be in the form of a
capsule, sachet, paper or other container. When the excipient
serves as a diluent, it can be a solid, semi-solid, or liquid
material, which acts as a vehicle, carrier or medium for the active
ingredient. Thus, the compositions can be in the form of tablets,
pills, powders, lozenges, sachets, cachets, elixirs, suspensions,
emulsions, solutions, syrups, aerosols (as a solid or in a liquid
medium), ointments containing for example up to 10% by weight of
the active compound, soft and hard gelatin capsules, suppositories,
sterile injectable solutions, and sterile packaged powders.
In preparing a formulation, it may be necessary to mill the active
compound to provide the appropriate particle size prior to
combining with the other ingredients. If the active compound is
substantially insoluble, it ordinarily is milled to a particle size
of less than 200 mesh. If the active compound is substantially
water soluble, the particle size is normally adjusted by milling to
provide a substantially uniform distribution in the formulation,
e.g. about 40 mesh.
Some examples of suitable excipients include lactose, dextrose,
sucrose, sorbitol, mannitol, starches, gum acacia, calcium
phosphate, alginates, tragacanth, gelatin, calcium silicate,
microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water,
syrup, and methyl cellulose. The formulations can additionally
include: lubricating agents such as talc, magnesium stearate, and
mineral oil; wetting agents; emulsifying and suspending agents;
preserving agents such as methyl- and propylhydroxybenzoates;
sweetening agents; and flavoring agents. The compositions of the
invention can be formulated so as to provide quick, sustained or
delayed release of the active ingredient after administration to
the patient by employing procedures known in the art.
The compositions are preferably formulated in a unit dosage form,
each dosage containing from about 0.05 to about 100 mg, more
usually about 1.0 to about 30 mg, of the active ingredient. The
term "unit dosage form" refers to physically discrete units
suitable as unitary dosages for human subjects and other mammals,
each unit containing a predetermined quantity of active material
calculated to produce the desired therapeutic effect, in
association with a suitable pharmaceutical excipient.
The active compound is effective over a wide dosage range. For
examples, dosages per day normally fall within the range of about
0.01 to about 30 mg/kg of body weight. In the treatment of adult
humans, the range of about 0.1 to about 15 mg/kg/day, in single or
divided dose, is especially preferred. However, it will be
understood that the amount of the compound actually administered
will be determined by a physician, in the light of the relevant
circumstances, including the condition to be treated, the chosen
route of administration, the actual compound administered, the age,
weight, and response of the individual patient, and the severity of
the patient's symptoms, and therefore the above dosage ranges are
not intended to limit the scope of the invention in any way. In
some instances dosage levels below the lower limit of the aforesaid
range may be more than adequate, while in other cases still larger
doses may be employed without causing any harmful side effect,
provided that such larger doses are first divided into several
smaller doses for administration throughout the day.
Formulation Example 1
Hard gelatin capsules containing the following ingredients are
prepared:
______________________________________ Quantity Ingredient
(mg/capsule) ______________________________________ Active
Ingredient 30.0 Starch 305.0 Magnesium stearate 5.0
______________________________________
The above ingredients are mixed and filled into hard gelatin
capsules in 340 mg quantities.
Formulation Example 2
A tablet formula is prepared using the ingredients below:
______________________________________ Quantity Ingredient
(mg/tablet) ______________________________________ Active
Ingredient 25.0 Cellulose, microcrystalline 200.0 Colloidal silicon
dioxide 10.0 Stearic acid 5.0
______________________________________
The components are blended and compressed to form tablets, each
weighing 240 mg.
Formulation Example 3
A dry powder inhaler formulation is prepared containing the
following components:
______________________________________ Ingredient Weight %
______________________________________ Active Ingredient 5 Lactose
95 ______________________________________
The active mixture is mixed with the lactose and the mixture is
added to a dry powder inhaling appliance.
Formulation Example 4
Tablets, each containing 30 mg of active ingredient, are prepared
as follows:
______________________________________ Quantity (mg/ Ingredient
tablet) ______________________________________ Active Ingredient
30.0 mg Starch 45.0 mg Microcrystalline cellulose 35.0 mg
Polyvinylpyrrolidone 4.0 mg (as 10% solution in water) Sodium
carboxymethyl starch 4.5 mg Magnesium stearate 0.5 mg Talc 1.0 mg
Total 120 mg ______________________________________
The active ingredient, starch and cellulose are passed through a
No. 20 mesh U.S. sieve and mixed thoroughly. The solution of
polyvinylpyrrolidone is mixed with the resultant powders, which are
then passed through a 16 mesh U.S. sieve. The granules so produced
are dried at 50.degree.-60.degree. C. and passed through a 16 mesh
U.S. sieve. The sodium carboxymethyl starch, magnesium stearate,
and talc, previously passed through a No. 30 mesh U.S. sieve, are
then added to the granules which, after mixing, are compressed on a
tablet machine to yield tablets each weighing 120 mg.
Formulation Example 5
Capsules, each containing 40 mg of medicament are made as
follows:
______________________________________ Quantity (mg/ Ingredient
capsule) ______________________________________ Active Ingredient
40.0 mg Starch 109.0 mg Magnesium stearate 1.0 mg Total 150.0 mg
______________________________________
The active ingredient, cellulose, starch, and magnesium stearate
are blended, passed through a No. 20 mesh U.S. sieve, and filled
into hard gelatin capsules in 150 mg quantities.
Formulation Example 6
Suppositories, each containing 25 mg of active ingredient are made
as follows:
______________________________________ Ingredient Amount
______________________________________ Active Ingredient 25 mg
Saturated fatty acid glycerides to 2,000 mg
______________________________________
The active ingredient is passed through a No. 60 mesh U.S. sieve
and suspended in the saturated fatty acid glycerides previously
melted using the minimum heat necessary. The mixture is then poured
into a suppository mold of nominal 2.0 g capacity and allowed to
cool.
Formulation Example 7
Suspensions, each containing 50 mg of medicament per 5.0 ml dose
are made as follows:
______________________________________ Ingredient Amount
______________________________________ Active Ingredient 50.0 mg
Xanthan gum 4.0 mg Sodium carboxymethyl cellulose (11%) 50.0 mg
Microcrystalline cellulose (89%) Sucrose 1.75 g Sodium benzoate
10.0 mg Flavor and Color q.v. Purified water to 5.0 ml
______________________________________
The medicament, sucrose and xanthan gum are blended, passed through
a No. 10 mesh U.S. sieve, and then mixed with a previously made
solution of the microcrystalline cellulose and sodium carboxymethyl
cellulose in water. The sodium benzoate, flavor, and color are
diluted with some of the water and added with stirring. Sufficient
water is then added to produce the required volume.
Formulation Example 8
Capsules, each containing 15 mg of medicament, are made as
follows:
______________________________________ Quantity (mg/ Ingredient
capsule) ______________________________________ Active Ingredient
15.0 mg Starch 407.0 mg Magnesium stearate 3.0 mg Total 425.0 mg
______________________________________
The active ingredient, cellulose, starch, and magnesium stearate
are blended, passed through a No. 20 mesh U.S. sieve, and filled
into hard gelatin capsules in 425 mg quantities.
Formulation Example 9
An intravenous formulation may be prepared as follows:
______________________________________ Ingredient Quantity
______________________________________ Active Ingredient 250.0 mg
Isotonic saline 1000 ml ______________________________________
Formulation Example 10
A topical formulation may be prepared as follows:
______________________________________ Ingredient Quantity
______________________________________ Active Ingredient 1-10 g
Emulsifying Wax 30 g Liquid Paraffin 20 g White Soft Paraffin to
100 g ______________________________________
The white soft paraffin is heated until molten. The liquid paraffin
and emulsifying wax are incorporated and stirred until dissolved.
The active ingredient is added and stirring is continued until
dispersed. The mixture is then cooled until solid.
Formulation Example 11
Sublingual or buccal tablets, each containing 10 mg of active
ingredient, may be prepared as follows:
______________________________________ Quantity Per Ingredient
Tablet ______________________________________ Active Ingredient
10.0 mg Glycerol 210.5 mg Water 143.0 mg Sodium Citrate 4.5 mg
Polyvinyl Alcohol 26.5 mg Polyvinylpyrrolidone 15.5 mg Total 410.0
mg ______________________________________
The glycerol, water, sodium citrate, polyvinyl alcohol, and
polyvinylpyrrolidone are admixed together by continuous stirring
and maintaining the temperature at about 90.degree. C. When the
polymers have gone into solution, the solution is cooled to about
50.degree.-55.degree. C. and the medicament is slowly admixed. The
homogenous mixture is poured into forms made of an inert material
to produce a drug-containing diffusion matrix having a thickness of
about 2-4 mm. This diffusion matrix is then cut to form individual
tablets having the appropriate size.
Another preferred formulation employed in the methods of the
present invention employs transdermal delivery devices ("patches").
Such transdermal patches may be used to provide continuous or
discontinuous infusion of the compounds of the present invention in
controlled amounts. The construction and use of transdermal patches
for the delivery of pharmaceutical agents is well known in the art.
See, e.g., U.S. Pat. No. 5,023,252, issued Jun. 11, 1991, herein
incorporated by reference. Such patches may be constructed for
continuous, pulsatile, or on demand delivery of pharmaceutical
agents.
Frequently, it will be desirable or necessary to introduce the
pharmaceutical composition to the brain, either directly or
indirectly. Direct techniques usually involve placement of a drug
delivery catheter into the host's ventricular system to bypass the
blood-brain barrier. One such implantable delivery system, used for
the transport of biological factors to specific anatomical regions
of the body, is described in U.S. Pat. No. 5,011,472, issued Apr.
30, 1991, which is herein incorporated by reference.
Indirect techniques, which are generally preferred, usually involve
formulating the compositions to provide for drug latentiation by
the conversion of hydrophilic drugs into lipid-soluble drugs or
prodrugs. Latentiation is generally achieved through blocking of
the hydroxy, carbonyl, sulfate, and primary amine groups present on
the drug to render the drug more lipid soluble and amenable to
transportation across the blood-brain barrier. Alternatively, the
delivery of hydrophilic drugs may be enhanced by intra-arterial
infusion of hypertonic solutions which can transiently open the
blood-brain barrier.
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